Preliminary observations indicate that objective lung sound analysis provides important noninvasive diagnostic information of common pulmonary conditions. Such analysis can also be used to validate the accuracy of observers using stethoscopes and improve the learning process. This type of analysis can now be readily performed with a Stethograph, an innovative device that makes visual displays of the sounds and permits precise semiautomatic measurements of sonic waveform features. Stethophonics, a small business, proposes to market Stethographs presuming that these preliminary observations are confirmed in a larger group of patients. In this Phase I study, the lung sounds of 100 patients will be examined; 20 in each of the following categories: interstitial fibrosis, congestive heart failure, chronic obstructive pulmonary disease, pneumonia and normal. Independent classification of these lung sound studies will be compared to the clinical diagnosis. The teaching value will be assessed by measuring pre and post test results during direct auscultation and on listening to tape recordings of observers provided with Stethograms as compared to observers taught standard clinical methods alone. The effect of visual displays on observer variability will also be studied. Phase II will include a market survey of teaching institutions and the industrial setting where ausculation already has proven value.